A review of dipterocarps - Center for International Forestry Research

Conservation of Genetic Resources in the dipterocarpaceae 53
range may often show more genetic variation than
peripheral populations due to a higher rate of gene
exchange in central populations.
Fourth, the effect of genetic diversity and inbreeding
on population viability should be an area of utmost
concern. Are reduced levels of genetic diversity and
outcrossing associated with a decline in fitness? Decrease
in fitness may be manifested as reduction in fruit and
seed set, seedling vigour and overall recruitment and
regeneration. It is thus critical to link genetic studies and
demographic studies. Comparative studies of gene flow
in fragmented and contiguous forests, described earlier,
should incorporate comparative studies of the effects of
genetic variation and inbreeding on reproductive output
and regeneration. Mass flowering in dipterocarps also
offers opportunities to gain insights into the relationship
between genetic diversity and population recruitment.
Sporadic flowering in off years may reduce the effective
population size, increase inbreeding and mortality of seeds
due to predation and lead to a disproportionately low level
of recruitment. Comparative genetic and demographic
studies during mass and sporadic off year flowering can
provide useful information about possible effects of
reduction in population size.
Fifth, many species of dipterocarps display
intraspecific variation in chromosome number and
apomixis. However, the frequency of chromosomal
variants or apomixis within or among populations is not
documented. There are now molecular tools to rapidly
assay populations for the incidence of chromosomal
variation, apomixis and hybridisation.
Site-specific Research
The rates of deforestation vary widely among the regions.
Species diversity of dipterocarps is also not uniform
throughout South and Southeast Asia. Thus, from a
geographical perspective, high priority should be
accorded to regions that are undergoing rapid
deforestation and those that have very high species
richness.
The Philippines, Sri Lanka and the Western Ghats of
south India have been converted into other forms of land
uses at a high rate during the last fifty years. These areas
have certainly lost unique populations and perhaps species
of dipterocarps. In such areas, there is an immediate need
to assess the conservation status of various taxa building
on P. Ashton’s earlier review. Sri Lanka particularly
deserves serious consideration because of the high
degree of endemism: 6 out of 7 genera and 45 out of 46
species of dipterocarps are endemic to the country.
The greatest species diversity in the family is found
in northwest Borneo. However, much of the cytology
and genetic research cited in this paper has been
conducted on species from Peninsular Malaysia and Sri
Lanka. Data from genetics and population biology of the
taxa that occur in northwest Borneo should provide useful
insights into mechanisms regulating differentiation
within and among species.
Institutional Capability and Constraints
P.S. Ashton , J. Liu, P. Hall and their associates (Harvard
University), S. Appanah, H. Chan, and others (Forest
Research Institute Malaysia (FRIM)) have played a key
role in advancing our knowledge of the systematics,
biogeography, and ecology of the family. Research in
systematics and ecology is being continued at Harvard
University. At FRIM the scope of research in genetic
resources has been recently enlarged to include such
areas as molecular evolution and population genetics.
In Sri Lanka, N. Gunatilleke and S. Gunatilleke at
the University of Peradeniya have a major research
programme on conservation biology of dipterocarps.
This programme includes research on population biology
and population genetics. N. Gunatilleke and S.
Gunatilleke have collaborated with P. Ashton (Harvard
University), K. Bawa and D. Murawski (University of
Massachusetts, Boston).
Another major centre of research on population
biology and genetics of dipterocarps is the Kyoto
University. T. Inoue, K. Momose and R. Terauchi are
involved in detailed studies of phenology, pollination
biology and genetics of dipterocarp species in Sarawak.
The work is a part of a major programme on canopy
research in dipterocarp forests.
S. Dayanandan and R. Primack (Boston University)
are working in collaboration with P. Ashton on a diverse
range of issues in dipterocarp biology, from molecular
biology to population dynamics.
Recently, the Center for International Forestry
Research (CIFOR) and International Plant Genetic
Resources Institute (IPGRI) have initiated a project on
population genetics, specifically on the effects of forest
fragmentation, logging and non-logging disturbance on
genetic diversity of some dipterocarps. This programme